Abstract Therepairoflargecartilagelesions,whicharecontraindicatedforcurrentlyavailablefirst-linetissue regenerationtechniques,remainsasignificantclinicalproblemwithfewgoodtreatmentoptions.Previouswork atCytexhasfocusedonthedevelopmentofa3Dmicrowoventextilescaffoldforcartilagerepair,designedto functionimmediatelyafterimplantationwhileencouragingcellingrowth,proliferation,andsubsequenttissue development.Whencombinedwithmesenchymalstemcells(MSCs),wehavedemonstratedtheabilitytoform biomechanicallyfunctionalimplantsforthetreatmentoflargecartilagelesions,includingresurfacingthe femoralcondyles.However,forastemcell-basedcartilageimplanttobesuccessfulintheosteoarthritic(OA) joint,itmustwithstandthethehighdegreeofinflammationandtheassociatedcatabolicanddegenerative environmentfoundindiseasedjoints.Theobjectiveofthisproposalistoaddananti-inflammatorycapabilityto ourconstructinordertoprotecttheengineeredtissuesfromthehostilejointenvironment.Wewilltransduce theMSCsinourimplantwithaninflammation-responsivepromoterthatwilldrivetheexpressionofInterleukin 1(IL-1)receptorantagonist(IL-1Ra)orsolubletumornecrosisfactor(TNF)receptor(sTNFR),natural modulatorsthatinhibittheinflammatorysignalingofIL-1andTNF?,respectively.Theresultingcartilage constructwillprovideinflammationresistanceonlywheninflammatorysignalingispresent,thuseliminatingthe needforexogenousinjectionsandthepotentialsideeffectsassociatedwithlong-termadministrationofanti- cytokinetherapy.InAim1,wewillexamineourlentiviraltransductionconditionsinanefforttominimizetherisk ofgeneticsideeffectsintheMSCs.Theresultingcartilageconstructswillalsobeanalyzedtoensurethatthey containnoactivelentiviralparticles,whichcouldbereleaseduponimplantation,therebyvalidatingtheclinical safetyofthegeneticapproach.InAim2,wewilluseourbiomimeticcartilageimplantstoresurfacethemedial femoralcondyleinagoatmodelofunicompartmentalosteoarthritis.Ourcurrenttissueengineeredimplantwill becomparedtoimplantsinwhichtheMSCpopulationhasbeentransducedtoexpressanti-cytokine therapeuticsineitheraconstant,oraninflammation-responsivemanner.Allanimalswillbeevaluatedat3,6,9, and12-monthtimepointsfollowingrepairthroughclinicallyrelevantmeasuresoffunction,pain,andimaging usingX-RaysandMRI.Atsacrifice,jointtissueswillbeassessedhistologicallyandbiomechanicallytoquantify degradativechangesandOAprogression.Serum,synovialfluid,andsynoviumwillbeanalyzedforbiomarkers ofosteoarthritis,aswellasforadverseinflammatoryreactionsandtotestforweardebrisinthejoint. Additionally,allmajororgansystemswillbeexaminedtoassessthesafetyofimplantingtransducedcellsand utilizinglocalizedanti-cytokinetherapy.Ultimately,thisproposalwilldevelopacartilageresurfacingproduct thatisnotonlybeabletofunctionmechanicallywithinthejointbutwillalsoprotectitselfandsurrounding tissuesfrominflammatorysignaling,andhopefullypreventfurtherOAprogression.